Dry battery seal and terminal connection

ABSTRACT

In a cylindrical dry cell, the cathode body comprising depolarizing material and electrolyte is completely isolated from the anode compartment by a sealing gasket which engages a generally washer-shaped subseal which fits snugly in the cylindrical can and holds down the end portion of the paper separator which covers the cathode. The subseal also serves to prevent creepage of alkaline electrolyte solution to the cell sealing surfaces at the open end of the can. The gasket may also serve to continuously press the current collector against the terminal diaphragm of the cell for dependable electrical engagement therewith.

United States Patent 1191 Strauss et al.' Jan. 7, 1975 [5 DRY BATTERYSEAL AND TERMINAL 3,228,801 1/1966 Snyder l36/l07 x ON ON 3,338,7508/1967 Urry 136/107 3,558,356 l/l97l Jost [36/6 Inventors: Howard J-Strauss, Bloommgton, 3,762,956 10/1973 Gillespie 136/133 x Mmn.; EdwardS. Hill, Wickliffe, Ohm Primary ExaminerC. W. Lanham 731 Assignee: Gould1116., Mendota Heights, Minn. Assistant Examiner-Joseph A. walkowski.

I Attorney, Agent, or FirmDarbo, Robertson & [22] F1led. Apr. 13, 1973Vandenburgh [2i] Appl. No.: 350,819

Related U.S. Application Data [57] ABSTRACT [62] Division of Ser. No.176,940, Sept. 1, 1971, Pat. No. In a cylindrical dry cel he cathodebody comprising 3,836,400. depolarizing material and electrolyte iscompletely isolated from the anode compartment by a sealing gasket [52]U.S. Cl 136/175, 29/592, 136/167 which engages a generally washer-shapedsubseal {51] Int. Cl. H0lm 31/00 which fits snugly in the cylindricalcan and holds down [58] Field of Search 29/592, 204; 136/6, 83, the endportion of the paper separator which covers 136/107, 133, 167, 168, 169,175, I77, 178 the cathode. The subseal also serves to prevent creepageof alkaline electrolyte solution to the cell sealing [56] ReferencesCited surfaces at the open end of the can. The gasket may UNITED STATESPATENTS also serve to continuously press the current collector 3 016 414H1962 Priebe A 36/107 against the terminal diaphragm of the cell fordepend- 330903824 5/1963 Reilly et al 136/107 able elecmca engagemettherewth- 3,l43,44l 8/1964 Coleman et al..,. l36/l78 3,219,487 11/1965Krouse et al 136/107 3 Clams 4 Drawmg F'gures PATENTED JAN 7 DRY BATTERYSEAL AND TERMINAL CONNECTION This is a division of application Ser. No.176,940, filed Sept. 1, 1971, now U.S. Pat. No. 3,836,400.

BACKGROUND AND SUMMARY OF THE INVENTION Dry cells having alkalineelectrolytes and anode bodies of the slurry type present specialproblems which must be met to ensure the production of a satisfactorycell. Innovative measures must be taken to avoid the consequences of thetendency of the alkaline electrolyte solution to creep along thesurfaces of the metal can which might otherwise prevent the propersealing of the cell. If not dependably separated, movement or growth ofthe anode slurry can result in the internal short circuiting of thecell. The problem of electrical connection of the external negativeterminal with the anode body is an ever present one and many more orless costly and dependable arrangements have been suggested for thispurpose.

The principal object of the invention is to provide dependablestructural separation between the cathode and the anode of a cylindricaldry cell having an alkaline electrolyte and an anode of the slurry type.To this end, a subseal is provided which fits snugly within the cell,holding the out-turned end of the paper separator in position coveringthe top of the cathode body. A cell seal gasket has a truncated conicalportion which converges downwardly and engages the subseal to close offany communication between the cathode and anode compartments of thecell.

A further object of the invention is to provide means for continuouslypressing the anode current collector upwardly against the underside ofthe terminal diaphragm of the cell to ensure good and dependableelectrical connection therewith. The desired pressure is provided by anauxiliary but integral part of the seal gasket which may be stressed andloaded like a spring in the assembly of the cell and/or which may beurged upwardly against the diaphragm by the subseal pressing against theauxiliary gasket structure.

DESCRIPTION OF THE DRAWING In the accompanying drawing,

FIG. 1 is a cross sectional view of a can-cathode subassembly with thesubseal in position;

FIG. 2 is a cross-sectional view of the upper portion of a cell showingthe structure for separating the cathode and anode compartments;

FIG. 3 is a cross-sectional view of a cell showing an alternativeconstruction, and

FIG. 4 is a cross-sectional view of the seal gasket of the cell of FIG.3.

DESCRIPTION OF SPECIFIC EMBODIMENTS Except for the novel subsealingarrangement, the dry cell illustrated in FIGS. 1 and 2 are of knownconstruction. The top seal and venting arrangement is essentially shownin U.S. Pat. No. 3,143,441.

The cell is manufactured by first producing the cathodecan assemblyillustrated in FIG. 1. The annular cathode body 1 of depolarizingmaterial is inserted into steel can 2 and a separator 3 of paper ofother suitable material is positioned to cover interior surfaces of thecathode. The separator may be formed as the sheet material is insertedinto the cell or may be preformed, as

desired. In either case, the top portion 4 of the separator is turned toextend radially outwardly to cover the top of the cathode body 1.Preferably the separator extends to the can, as shown. Subseal washer 5ofa suitable semi-rigid, moderately resilient material such aspolyethylene, is seated snugly in the can upon the outturned portions 4of the separator.

The sub-assembly thus formed is ready for insertion of the balance ofthe active materials of the cell, provision for negative terminalconnections and the closing and sealing of the cell.

After insertion of the proper quantity of alkaline electrolyte, e.g.,potassium hydroxide dissolved in water and a small proportion of zincoxide, the anode slurry 6 is placed in the cell. If the can was notcrimped at 7 following insertion of subseal washer 5, it may be crimpedat this stage ofmanufacture after which gasket 8, current collector 9with diaphragm 10 and cap 11 are placed in position. The cell is thenclosed and permanently sealed by applying radial pressure to the topportion 12 of the can and crimping the edge portions of the gasket andcan in upon the periphery of cap 11. The cell, so sealed, is ready forservice.

The truncated conical bottom portion 13 of gasket 8 and the cathodesubseal washer 5 are dimensioned and formed to mutually engage at theinner periphery of washer 5 as shown. This resilient but firm contactpositively separates the anode compartment of the cell from any possiblecommunication with the cathode. No part of the anode slurry can escapeto short circuit the cell.

In the cell illustrated in FIG. 3, an additional, reentrant truncatedconical section 14 is provided as an integral part of gasket 8a. The topedge of conical section 14 engages the ends of U-shaped currentcollector 15, providing contact pressure necessary for dependableelectrical connection of the current collector with diaphragm 16 which,in turn, is in electrical contact with cap 17 which serves as thenegative terminal of the cell. The cell is closed and permanently sealedby inward radial compression of the top portion of the can and theapplication of steel ring 18 to ensure enduring sealing pressure.

As has been described with reference to the cell of FIGS. 1 and 2,truncated conical section 13 of gasket 8a engages the inner periphery ofsubseal washer S to close off the anode compartment from any possiblepassage of any part of the anode slurry to the cathode.

The preferred form of gasket is shown separately in FIG. 4. In thisnormal, unstressed configuration, the upper edge 19 is in a plane abovethat of shoulder 20 which latter establishes the level of the bottomsurface of diaphragm 16. When the cell is assembled, diaphragm 16 isforced downwardly to seat upon shoulder 20 against the opposing force ofgasket section 14. The result is a pressure contact of substantialmagnitude between the hook ends of anode collector l5 and diaphragm l6.

Since nylon may be provided as a relatively hard and stiff plasticresistant to cold flow under'continuing stress, this material ispreferably used in the manufacture of gasket 8a.

This desirable electrical contact pressure is augmented by theresilient'pressure applied to section 13 of the gasket by the resilientsubseal washer 5. As the gasket is forced down against washer 5 toprovide the closure engagement above described, the resilient pressureof the washer tends to urge section 13, and therefore section 14, of thegasket inwardly and upwardly. Thus, a continuing pressure is provided toensure the necessary electrical contact pressure between the currentcollector and diaphragm 16 even though cold flow of the nylon materialover a period of time may result in some relaxing of the pressureinitially provided by the stressing of the gasket structure.

It should be noted that although gasket 8a is shown and described ashaving the re-entrant conical section sufficiently long to extend, innormal unstressed condition, to a plane above that of the shoulder 20,this is not an indispensable feature of construction since the pressureexerted by the subseal washer against section 13 of the gasket iscapable of providing the desired pressure of the current collector 15against the diaphragm 16 without the above-described prestressing of thegasket structure.

We claim:

1. The method of making an electric dry cell comprising a cylindricalcan having a subseal and a cell closure and terminal structure includinga gasket having a stiffly flexible frustro-conical section dependingfrom the peripheral portion thereof, which method combarrier to thespaces on each side of the area of engagement and thereafter completingthe final closure of the cell.

2. The method of making an electric dry cell comprising a cylindricalcan having a subseal and a cell closure and terminal structure includinga terminal connector member, a sealing gasket and a current collectorand wherein the gasket includes stiffly flexible depending andre-entrant sections integral with the gasket, the re-entrant section inthe normal unstressed gasket terminating in a plane higher than that inthe assembled I cell, which method comprises the steps of assemblyingprises the steps of assemblying the cell to the point of closureincluding the insertion of a resilient subseal washer spaced below theopen end of the can and engaging the can with resilient pressure,inserting the gasket and the rest of the cell closure and terminalstructure and forcing the same downwardly whereby the frustro-conicalsection of the gasket resiliently engages the inner periphery of thesubseal washer to provide a the cell to the point of closure includingthe insertion ofa resilient subseal washer spaced below the open end ofthe can and engaging the can with resilient pressure, inserting thegasket, inserting the current collector and arranging the ends thereofover the end of the gasket re-entrant section, placing the terminalconnector member in position in engagement with the ends of the currentcollector and thereafter completing the cell including forcing thegasket and the terminal connector member downwardly for resilientengagement of the depending section of the gasket with the subsealwasher and distorting the gasket sections to stress the same whereby toprovide continuous upward pressure against the ends of the currentcollector for good electrical contact between the current collector andthe terminal connector member.

3. The method of claim 2 wherein the ends of the current collector arehook-shaped and are hooked over the end of the gasket re-entrantsection.

l =l l=

1. The method of making an electric dry cell comprising a cylindricalcan having a subseal and a cell closure and terminal structure includinga gasket having a stiffly flexible frustroconical section depending fromthe peripheral portion thereof, which method comprises the steps ofassemblying the cell to the point of closure including the insertion ofa resilient subseal washer spaced below the open end of the can andengaging the can with resilient pressure, inserting the gasket and therest of the cell closure and terminal structure and forcing the samedownwardly whereby the frustro-conical section of the gasket resilientlyengages the inner periphery of the subseal washer to provide a barrierto the spaces on each side of the area of engagement and thereaftercompleting the final closure of the cell.
 2. The method of making anelectric dry cell comprising a cylindrical can having a subseal and acell closure and terminal structure including a terminal connectormember, a sealing gasket and a current collector and wherein the gasketincludes stiffly flexible depending and re-entrant sections integralwith the gasket, the re-entrant section in the normal unstressed gasketterminating in a plane higher than that in the assembled cell, whichmethod comprises the steps of assemblying the cell to the point ofclosure including the insertion of a resilient subseal washer spacedbelow the open end of the can and engaging the can with resilientpressure, inserting the gasket, inserting the current collector andarranging the ends thereof over the end of the gasket re-entrantsection, placing the terminal connector member in position in engagementwith the ends of the current collector and thereafter completing thecell including forcing the gasket and the terminal connector memberdownwardly for resilient engagement of the depending section of thegasket with the subseal washer and distorting the gasket sections tostress the same whereby to provide continuous upward pressure againstthe ends of the current collector for good electrical contact betweenthe current collector and the terminal connector member.
 3. The methodof claim 2 wherein the ends of the current collector are hook-shaped andare hooked over the end of the gasket re-entrant section.